Pressureless sintering of ZrC with variable stoichiometry

Abstract

This paper presents the experiments on the synthesis of zirconium carbide (ZrC) using carbothermal reduction of zirconia (ZrO2). The ratio of ZrO2:C is used to adapt ZrC x O y with x < 1 or ZrC + C. The modification of ZrC x O y and the total carbon amount allows the use of pressureless sintering method in combination with sintering temperatures ≤ 2000 °C. Fully densified ZrC products are obtained. The relevant details of ZrC formation are investigated by X-ray diffraction (XRD). The sintered products are characterized by XRD, field emission scanning electron microscopy (FESEM), as well as mechanical and electrical methods. XRD and FESEM investigations show that ZrC x O y is formed during the manufacturing process. The grain size and additional zirconia or carbon are related to the ZrO2:C ratio of the starting powder mixture. Bending strength up to 300 MPa, Young’s modulus up to 400 GPa, fracture toughness up to 4.1 MPa·m1/2, and electrical resistance at room temperature around 10−4 Ω·cm are reached by the pressureless sintered ZrC.